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<html lang="en">
  <head>
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    <meta name="viewport" content="width=device-width, initial-scale=1.0" />
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    <style>
      header,
      nav {
        width: 800px;
        height: 120px;
        background-color: blue;
        margin: 50px auto;
        border-radius: 20px;
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  <body>
    <header></header>
    <nav></nav>
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